It has long been known that certain microbial materials are advantageous in the rhizosphere of plants. For example, Rhizobium is one such microbial material. U.S. Pat. No. 4,155,737 (Dommergues, et al.) shows Rhizobium embedded in a polyacrylamide gel. The gel has a low water content and may be crushed to a particulate form. The particles may be disbursed in soil. This is generally referred to as soil inoculation. A wide variety of other microbial materials have been similarly used, for example, ectomycorrhizal fungus has been entrapped in a polymeric gel. A clay is added to the gel to result in a solid microgranule product. This product may be disbursed in a bed of seedlings and the fungus stimulates the growth of the seedlings. Efficiency in a Forest Nursery of an Ectomycorrhizal Fungus Inoculum produced in a Fermentor and Entrapped in Polymeric Gels, Tacon, Jung, Mugnier, Michelot and Mauperin, 1985, Can. J. Bot. 63:1664-1668. While prior methods have been somewhat effective, such methods have had inherent shortcomings. For example, the microorganisms tend to be inactive and do not multiply significantly in the low moisture granules. Also the plant roots must grow, extending their root systems, before they encounter the granules, thus the plant is slow in initiating the symbiotic relationships.